Beverage containers are known that have an upper end opening that is covered and sealed with a lid. In these types of beverage containers, the container is filled with the beverage after the container interior has been sterilized to provide an aseptic state.
Conventional lids for these types of containers typically take one of several different forms. One type of lid, a so-called peelable seal type (hereinafter referred to as a membrane type lid) which is made of a sheet including a stretched PET (polyethylene terephthalate) film, is laminated on the surface of an aluminum foil, etc. and an easy peel layer is provided on the side which is intended to contact the container. The lid is mounted to cover an open upper end of the container and is fuse-bonded in place by heating.
Another type of lid involves a sheet that is designed to cover the open upper end of the container. The sheet is provided with an opening that serves as a drinking-hole. The lid has a pull tab formed from a small piece of material made of a PET/aluminum foil having an easy peel layer and the lid is adapted to cover the opening in the lid.
Another form of lid is one in which the lid is shaped by draw-forming an aluminum foil.
A still further type of lid is prepared by so-called insert injection molding in which an aluminum foil coated with PE (polyethylene), etc. is previously inserted into a mold, and the lid having the desired opening means in the aluminum foil is molded by injection molding.
Unfortunately, the various lid constructions described above are susceptible of certain disadvantages and drawbacks. For example, in the case of the membrane type lid described above, the seal strength between the lid and the container should be high enough to withstand handling during transportation of the products. On the other hand, the opening strength required to remove the lid from the container should be sufficiently low so as to facilitate opening of the container. Unfortunately, it is quite difficult to balance both of these requirements.
Further, since the opening formed after removal of the lid from the container is rather large, the beverage is apt to spill in certain situations, such as when the beverage in the container is being consumed while walking.
In the case of the above-described lid provided with a pull tab, the aforementioned problems associated with the membrane type lid are not as prevalent. However, since the pull tab is formed of a membrane-type sheet, the lid fails to provide a high quality feeling or appearance, but rather gives a rather "cheap-looking" impression to the lid.
The lid that is formed by draw-forming an aluminum foil is disadvantageous in that it is relatively costly.
The last type of lid described above, although useful from the standpoint of providing gas-barrier properties, is problematic in that the coating of aluminum foil with PE is complicated, and the lid has a tendency to be easily peeled.
In addition to the foregoing, most of the above-described conventional lids are removed and separated from the beverage container after the container has been opened so that a disposal problem exists. Even in the case of a lid which is not removed from the container at the time of opening, the current technology is such that the opened container cannot be sealed again with the lid.